/Engine/Source/Runtime/Slate/Public/Framework/MultiBox/MultiBox.h
The visibility of the drop location indicator of a drag and drop for a block
[EVisibility](API\Runtime\SlateCore\Layout\EVisibility) GetCustomizationBorderDragVisibility ( const [FName](API\Runtime\Core\UObject\FName) InBlockName, const EMultiBlockType InBlockType, bool & bOutInsertAfter ) const